发明名称 |
Apparatus and method for a programmable adaptive output driver |
摘要 |
An adaptive output driver that uses a programmable Schmitt-trigger buffer to change the driver's operational response after it is manufactured. The adaptive output driver includes a primary driver that provides the primary current to drive an output signal into a load. A secondary driver for the adaptive output driver is enabled by the Schmitt-trigger buffer to provide an additional current to drive the load when the transitions between high and low states are slower than a predetermined slew rate. The programmable Schmitt-trigger buffer includes cells of pull-up and pull-down transistors that can be separately enabled. Each enabled cell causes an imbalance in the overall sizing ratio of activated pull-up and pull-down transistors; the amount of imbalance in the overall sizing ratio corresponds to the amount of hysteresis in the response of the Schmitt-trigger buffer. By programming the amount of hysteresis in the Schmitt-trigger buffer, the operation of the adaptive output driver can be modified to suit different loading conditions after manufacture. The programmable Schmitt-trigger buffer can be used in the input stage of an input/output driver employed with a microprocessor. Also, the programmable Schmitt-trigger buffer may be used with a distributed and weighted output driver to provide separate delays in the operation of selected output stages.
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申请公布号 |
US6353346(B1) |
申请公布日期 |
2002.03.05 |
申请号 |
US20000684754 |
申请日期 |
2000.10.06 |
申请人 |
NATIONAL SEMICONDUCTOR CORPORATION |
发明人 |
CHAN WAI CHEONG |
分类号 |
H03K3/3565;H03K17/16;H03K19/003;H03K19/0185;(IPC1-7):H03B1/00 |
主分类号 |
H03K3/3565 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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